1. Field of the Invention
The present invention relates, generally, to a security seal or lock, and more particularly to a tamper resistant seal with tamper indicating structure which can be visually inspected to determine whether tampering has occurred.
2. Background Information
Tamper resistant security seals are used to seal many objects such as electric meters, equipment, containers of any kind, as well as wagons, tugs, cisterns, mail bags and trunks. The seal should be very light and inexpensive to manufacture, and provide absolute security and easy handling. It must be impossible to detach the male seal part from the female seal part without visible damage, and the security wire must provide a clear warning that the seal has been twisted or pulled by force. Each seal must be marked with its number and other relevant data. Such a seal should be installed manually without any accompanying tools.
Conventional security seals are one-piece or two-piece devices made of either lead or plastic. A wire is fed through the components to be sealed and the ends of the wire are joined by the device, which is then crimped onto the wire. Unauthorized people can easily misuse such seals by enlarging the opening through which the wire passes, or, for two-piece devices, by disconnecting the body from the casing without damaging it. One wire end is then pulled out allowing easy entry into the protected room or access to the protected equipment. The wire is then pulled through the seal opening again and recrimped into the same condition as it was before the misusage.
U.S. Pat. No. 5,762,386 to Fuechrer discloses a safety seal with a male and female part that interlock. The male part has two longitudinal grooves that are connected by a passage at the bottom of the male part and a top portion with two openings through it, one opening corresponding to each groove. The wire is fed through one opening, along one groove, around the end of the male part, back up the other groove and out the other opening. While the Fuechrer device is more tamper resistant than conventional seals, it still has limitations and shortcomings. The wire makes only one bend around the end of the male part to limit resistance to the wire being pulled out. One embodiment of the device provides additional resistance by providing each channel with contoured sidewalls that cooperatively engage the rope-like outer surface of the wire. That requires the wire to have a contoured outer surface and the channel walls to be made with a mating contour. Another shortcoming occurs at the interface of the top portion of male part with the female part. The top portion only butts against the female part and there is clearance between the two which could allow the inserting of a suitable metal object, such as a knife or needle, for separating the male and female parts.
The present invention provides an the improved security seal which overcomes the limitations and shortcomings of the prior art.
The present invention provides a security seal with the female part, a male part and a security wire. The male part has a protective cover that receives the female part when the seal is installed. This prevents the mechanical separation of the male part from the female part. The male part has two grooves with a central opening between them through which the security wire passes after passing through the components being sealed. When the male part is inserted into the female part, two pairs of spurs on the male part engage knobs of the female part which prevents the male part from being pulled out of the female part. The male part and the female part of the seal are connected by a thread made of the same material to enable easier handling.
The advantages and characteristics of the present invention will become clear to those skilled in the art from the following description, claims and drawings.